Power System Fault Analysis using FaultReporting Data of Numerical Relays

Digital protection relays provide comprehensive fault reporting data for the analysis of power system faults and relay operations. Meanwhile the share of digital in the total relay population has reached a substantial figure. Thus the utilities can gather valuable information from relays throughout their grid. After a fault the operating personnel wants to obtain a most precise fault location to narrow the search for possible damage on the line and to cut the down time. An easy-to-use software system for relay fault records can provide the desired precision to the utility personnel. The system is open to fault records of any relay, which is accomplished via the COMTRADE data format.

Especially a new approach is included for fault location. This also covers transmission lines which consist of several segments of different properties like a cable continued with an overhead line. Furthermore it may also handle the typical asymmetry of untransposed overhead lines. By a special algorithm the load condition, the fault resistance and the zero-sequence impedance component and the mutual coupling, which all caused fault location tolerances in the past, can be effectively excluded such arriving at excellent precision.